DNA (Deoxyribonucleic Acid) is a polymer, meaning it is a large molecule made by linking together smaller repeating units. In the case of DNA, these repeating units are called nucleotides.
Each nucleotide consists of three parts:
- A phosphate group
- A deoxyribose sugar
- A nitrogenous base (adenine [A], thymine [T], cytosine [C], or guanine [G])
Nucleotides are joined together in a chain through phosphodiester bonds, forming a sugar-phosphate backbone with the nitrogenous bases sticking out. Two such strands pair up in a double helix structure, where complementary base pairing (A with T, C with G) holds them together through hydrogen bonds.
DNA’s polymer structure allows it to store genetic information, replicate accurately, and carry instructions for building proteins. This makes it the molecular blueprint of life, present in nearly every cell of every living organism.